Insulating cap for the joints of electrical conductors



July 31, 1928.

F. M. VAN GELDEREN INSULATING CAP 'r'on THE JOINTS OF ELECTRICALcbnnuc'rons Filed Oct. 18, 1927 v If A HI" by the in no prior patentPatented July 31, 1928.

FREDERIK MARINUS VAN GELDEREN, OF ENSCHEDE, NETHEDLAN DS.

INSULATING CA1 FOR THE JOINTS OF ELECTRICAL CONDUCTORS.

Application filed October 18, 1927. Serial No. 226,974.

This invention relates to insulating caps for the joints of electricalconductors, and more particularly to caps for insulating the bare endsof said conductors.

In my prior Patent No. 1,460,624, I have shown an insulating cap of thistype, said cap having an internally threaded cavity in which is locateda conical coil of spring wire. \Vhen thecap with the spring therein isscrewed on the bare ends of the con? doctors. the spring graduallyexpands in radial direction due to the introduction of the conductors,and this radial expansion brings more. or less of the intermediateportion of the spring into contact with the grooves of the threads ofthe insulating cap, the extent of the contact being determined size ofthe conductors upon which the cap and coil are threaded. Thus theconductors are firmly bound together and secured within the cap, ineffective electrical connection with one another;

In the use of a cap of this type, unless care is exercised by theelectrician to cut the ends of the wires exactly the right length, or ifthe tot. l diameter of the twisted wires is not suiliciently happensthat the ductors protrude beyond the innermost turn of the coil when thelatter has reached= the limit of its inward movement and strike thebottom of the cavity of the cap before the conductors are properly boundand tightly secured in the cap. As a result, further rotation of the capon the conductors produces no tightening eflect'and it becomesimpossible under such conditions to obtain a firm connection andreliable insulation.

It is an object of the present invention to avoid the aforesaiddifiiculty, and I have found that this object may be accomplishedby theprovision of a well or supplemental cavity at the bottom of theprincipal bore, or inner bore in case the cap is provided with inner andouter bores; a stop being provided for limiting the inward movement ofthe coil. 1

Another object of the invention is to provide a coil of such formthat itwill more effectively engage both the thread of the cap and the surfaceof the united conductors than results from the use of the coil shownmentioned. This is accomp ished by employing for the coil metal great,it frequently extreme ends of the con- I sula-ted.

form of a double cone,

wire which in cross section is squareor rhombic.

The invention will be more readily understood upon reference totheaccompanying which the cap has been applied, and

1 1g. 4 15a longitudinal section through,

another form of cap.

ln the drawing the numeral 1 represents an lnsulatmg cap. of porcelainor other suitable insulating material. The cap is hollow as shown and isprovided with an internal thread 2. As shown in Fig. 1, the thread 2extends almost to the open end of the cap, whereit opens into theshallow recess 3. 1n the -lorm illustrated in Figs. 2 and 3, the outerthreaded bore 3 is of substantial depth and its inner. end merges intothe inner bore about midway the entire depth of the cavity. The capshown in Fig. 4 is of the same general form as that shown in Figs. 2 and3, but the outer conical bore 3" is not provided with screw threads.

lhe wire coil is indicated in Figs. 2 and 3 by the numeral 4, and asillustrated is of polygonal cross section. Conveniently the section maybe square, but it may be rhombic or other form which will provide anouter angle on the coil for engagement with the thread of the cap and aninner angular portion for gripping the surface of the united conductorsto be connected and in- As shown in Fig. 2, only the larger convolutionat the inner end of the coil engages the threads 2 when the coil isthreaded into the cap. The coil has the general and the portionofsmallest diameter is preferably close to the inner end of the coil.The inner diameter at the smallest section must, of course, somewhatsmaller than the external diameter of the thinnest conductor joint whichmovement of the wire coil by abutment thickest conductor therewith ofthe inner end of the coil. Other modes of effecting engagement of thecoil.with the thread of the cap and for limiting the inward movement ofthe coil when the cap is applied to the conductor may be employed, butthat illustrated is quite prac- *tical and inexpensive.

' In the use of the device described, the cap '20 is applied to thebareends of the conductors to be united and rotated thereon. The wire coilengages the conductors and firmly unites, the same.

conductors progresses, the intermediate portion of the conical coil 4becomes .expanded and may ultimately engage the thread within the cap toa-greater or less extent. In the absence of the well, should thecomplete binding efiect and' the tightemng of the cap on the conductorsnot be effected before the ends of the latter strike the bottom of thebore, further rotation of the cap on the conductors is useless andanefiicient joint and insulation cannot be secured. By the'provision ofthe supplemental bore, however, the protruding extremities of theconductors are .free to move inward the necessary dis tance to permitthe coil to proceed .in its movement until interrupted by engagement ofits inner end with the stop 5 and to expand as completely as it willinto the groove in'the ca v; in other words, until the maximum bin ingeffect is produced. i

As shown In Figs. 2 and 3, the outer bore 3 is-threaded for'engagementwith the insulation (ion the separate conductors to provide a firm andsubstantially water-proof connection.

It willbe understood that the cap is useful for insulating the joints ofelectrical con ductors even if the wires happen to be cut so short thatthe well is not necessary, and it will be obvious, therefore, that. withthe use of the device described itis not necessary for the electricianto be particularly careful as to the length of wire ba'red beforeapplysaved. What I claim isi 7 ingthe cap, so that considerable time canbe '1. An insulating cap'of the type including a body. of insulatingmaterial having a cavity-therein, and a metallic insert in said diameterextending laterall As the inward movement of the provided with a wellbelow said cavity for receiving the ends of conductors which pro-,

trude beyond said cavity .and the metallic insert therein.

12. The combination with an insulating cap for the bare ends ofelectrical conductors, said .cap having a cavity therein provided withan internal thread, of a tapered coil of wire for receiving and bindingthe bare ends 'of the conductors when the cap is'applied thereto androtated and having a free end below the. turn of smallest to engage andmove along said thread, an a stop comprising the inner endof said threadfor limiting .the inward movement of'sai'd coil, said cap having a wellbelow said stop for receiving the ends of conductors which protrudebeyond said cavity. 7

3. The combination with an insulating capv for the bare ends ofelectrical conductors, said cap having a tapered cavity there- -1nprovided with an internal thread, of a conical coil of wire forreceiving and bindingthe bareiends of the conductors when the cap isapplied thereto and rotated, and having a freeend below the turn ofsmallest diameter extending laterally to engage and move along saidthread, and a stop comprising the inner end of said thread for limitmgthe inward movement'of said free end, sa d cap having a cylindrical wellbelow sald stop and of smaller diameter than the lower end of the cavityfor receiving the ends of conductors which protrude beyond said cavity.I

4. The combination with a hollow insulat mg cap for the bare ends ofelectrical cons ductors, said cap being internally screwthreaded, of ametal coil for receiving and bmdmg the bare ends of the conductors. whenthe cap is applied thereto and rotated and having means for the saidcoil being formed of wireof noncn cular cross-section which presents asharp thread-forming edge at the interior of the 5. An insulating ca asset- 'forth in claim 4, wherein the wire fiirmin said coil is ofpolygonal cross-section an arranged to and at the exterior of the coil.

i -In testimony whereof, I atli xl my signature. V

'FRIiJDERIK M." VAN GELDEREN. Y

having an internally I10 engaging the thread,

